TWI703549B - Voltage calibration circuit and method applied to display apparatus - Google Patents

Abstract

A voltage calibration circuit and method applied to a display apparatus are disclosed. The voltage calibration circuit includes a ramp voltage generator, a ramp counter and a timing controller. The ramp voltage generator is used to generate a ramp voltage. The ramp counter is coupled to the ramp voltage generator and starts counting when the ramp voltage generator generates the ramp voltage. The timing controller is coupled to the ramp voltage generator and the ramp counter respectively. When the ramp voltage rises to be equal to a reference voltage, the timing controller compares an instant count value of the ramp counter and a default value and selectively calibrates a rising slope of the ramp voltage generated by the ramp voltage generator according to a comparing result of the instant count value and the default value.

Description

Voltage correction circuit and voltage correction method applied to display device

The present invention relates to displays, and more particularly to a voltage correction circuit and voltage correction method applied to a display device.

Please refer to FIG. 1. FIG. 1 is a schematic diagram illustrating a driving method of a ramp source driver in a conventional display device.

As shown in Figure 1, in a traditional display device using OLED On Silicon microdisplay technology, the ramp source driver is a ramp voltage generator (Ramp voltage generator) RVG to generate a ramp voltage VRAMP through a buffer (Buffer) BF transmits the ramp voltage VRAMP to all data lines DL(X).

When the value counted by the Ramp counter RCT is equal to the preset value stored in the Data register DTR (for example, both are N), it will be immediately coupled to the buffer BF and data The switch SW between the lines DL(X) is turned off. At this time, the voltage on the data line DL(X) is the voltage value of the ramp voltage VRAMP generated by the ramp voltage generator RVG at that time.

However, in fact, the following factors in this circuit architecture cause The voltage values sampled on the data line are inconsistent.

First, the ramp voltage generator RVG basically charges a fixed capacitor through a fixed current source to generate a ramp voltage VRAMP with a fixed rising slope (as shown in FIG. 2) to provide different gray-scale voltages required by the display panel. However, since the current source and the capacitance will change with the variation of the manufacturing process, voltage, and temperature, the ramp voltage VRAMP provided by different driving circuits has different rising slopes, which need to be improved.

In addition, the ramp counter RCT is coupled to the oscillator OSC, and the oscillator OSC provides an oscillation frequency to the ramp counter RCT. Because the oscillator OSC also changes with the variation of the manufacturing process, voltage, and temperature, the time point (for example, T shown in FIG. 2) when the switch SW is turned off each time is inconsistent, resulting in the data line DL(X) The sampled ramp voltage values are also different, and it is urgent to improve.

In view of this, the present invention proposes a voltage correction circuit and a voltage correction method applied to a display device to effectively solve the above-mentioned problems encountered in the prior art.

A specific embodiment according to the present invention is a voltage correction circuit applied to a display device. In this embodiment, the voltage correction circuit includes a ramp voltage generator, a ramp counter, and a timing controller. The ramp voltage generator is used to generate ramp voltage. The ramp counter is coupled to the ramp voltage generator. When the ramp voltage generator generates the ramp voltage, the ramp counter starts counting. The timing controller is respectively coupled to the ramp wave voltage generator and the ramp wave counter. When the ramp voltage rises to be equal to the reference voltage, The timing controller compares the instant count value of the ramp counter with a preset value, and selectively corrects the rising slope of the ramp voltage generated by the ramp voltage generator according to the comparison result of the instant count value and the preset value.

In one embodiment, if the comparison result is that the real-time count value is equal to the preset value, the timing controller maintains the rising slope of the ramp voltage unchanged.

In one embodiment, if the comparison result is that the instantaneous count value is greater than the preset value, the timing controller increases the rising slope of the ramp voltage.

In one embodiment, if the comparison result is that the real-time count value is less than the preset value, the timing controller reduces the rising slope of the ramp voltage.

In one embodiment, the timing controller is coupled to the ramp voltage generator and provides a slope control signal to the ramp voltage generator to selectively correct the rising slope of the ramp voltage generated by the ramp voltage generator.

In one embodiment, the voltage correction circuit further includes a comparator. The two input terminals of the comparator are respectively coupled to the ramp voltage generator and the reference voltage. The comparator compares the ramp voltage with the reference voltage to determine whether the ramp voltage rises to be equal to the reference voltage.

In one embodiment, the voltage correction circuit further includes a D-type flip-flop. The two input terminals of the D-type flip-flop are respectively coupled to the output terminal of the comparator and the ramp counter. The output terminal of the D-type flip-flop is coupled to the timing controller. When the ramp voltage rises to be equal to the reference voltage, the D-type flip-flop will return the instant count value provided by the ramp counter to the timing controller.

In one embodiment, the voltage correction circuit further includes an oscillator, It is coupled to the ramp counter to provide the oscillation frequency to the ramp counter. The comparison result is related to the oscillation frequency.

Another specific embodiment according to the present invention is a voltage correction method. In this embodiment, the voltage correction method is applied to the display device. The display device includes a timing controller, a ramp voltage generator and a ramp counter. When the ramp voltage generator generates the ramp voltage, the ramp counter starts counting.

The voltage correction method includes the following steps: (a) When the ramp voltage rises to be equal to the reference voltage, record the real-time count value of the ramp counter and send it back to the timing controller; (b) the timing controller compares the real-time count value with the pre- And (c) the timing controller selectively corrects the rising slope of the ramp voltage generated by the ramp voltage generator according to the comparison result of step (b).

Compared with the prior art, the voltage correction circuit and voltage correction method applied to the display device according to the present invention can be judged based on the comparison result between the real-time count value of the ramp counter and the preset value when the ramp voltage rises to be equal to the reference voltage Whether the rising slope of the ramp voltage generated by the ramp voltage generator is too low or too high (or whether the oscillation frequency of the oscillator is too fast or too slow) and correct the rising slope of the ramp voltage accordingly, so it can be effective It solves the problem that the ramp voltage values sampled by different driving circuits on the display panel will also vary due to variations in process, voltage, and temperature.

The advantages and spirit of the present invention can be further understood from the following detailed description of the invention and the accompanying drawings.

S10~S18: steps

DTR: Data register

COMP: Comparator

SW: switch

OSC: Oscillator

RCT: Ramp counter

RVG: ramp voltage generator

BF: Buffer

DIN: Input data

VRAMP: ramp voltage

DL(X): data line

HS: Start signal

RCLK: Ramp clock signal

1~N: count value

D(X): data

T: time

SLC: Slope control signal

TCON: Timing Controller

VRAMP’: Digitally controlled ramp voltage

VREF: Reference voltage

S1: Comparator output signal

DFF: D-type flip-flop

FB: Feedback signal

SL1~SL3: rising slope

PVT: offset

T1~T3: time

FIG. 1 is a schematic diagram showing the driving method of the ramp source driver in the conventional display device.

FIG. 2 shows a timing diagram of when the ramp voltage VRAMP with a fixed rising slope starts to rise, the ramp counter RCT starts counting from 1 and counts to the preset value N at time T, and then turns off the switch.

FIG. 3 is a schematic diagram of a voltage correction circuit applied to a display device according to a preferred embodiment of the present invention.

Fig. 4 shows that when the ramp voltage rises to be equal to the reference voltage, the timing controller of the present invention compares the instantaneous count value of the ramp counter with the preset value and determines whether the ramp voltage generator should be corrected accordingly. Time chart of the rising slope of the ramp voltage.

FIG. 5 shows a flowchart of a voltage calibration method according to another preferred embodiment of the present invention.

A specific embodiment according to the present invention is a voltage correction circuit applied to a display device. In this embodiment, the display device includes a display panel, and the display panel can be an organic light-emitting diode panel, and can use OLED On Silicon microdisplay technology, but it is not limited to this.

Please refer to FIG. 3. FIG. 3 is a schematic diagram of the voltage correction circuit applied to the display device in this embodiment.

As shown in Figure 3, the voltage correction circuit applied to the display device includes a timing controller TCON, a ramp voltage generator RVG, an oscillator OSC, and a ramp counter RCT, comparator COMP and D-type flip-flop DFF. The timing controller TCON is coupled to the ramp voltage generator RVG; the ramp voltage generator RVG is coupled to one input terminal of the comparator COMP; the other input terminal of the comparator COMP is coupled to the reference voltage VREF; and the comparator COMP The output terminal and the ramp counter RCT are respectively coupled to the two input terminals of the D-type flip-flop DFF; the output terminal of the D-type flip-flop DFF is coupled to the timing controller TCON; the oscillator OSC is coupled to the ramp counter RCT.

In this embodiment, the ramp voltage generator RVG generates a digitally controlled ramp voltage VRAMP' to an input terminal of the comparator COMP, and the digitally controlled ramp voltage VRAMP' rises with time and has a fixed rising slope.

When the two input terminals of the comparator COMP receive the digitally controlled ramp voltage VRAMP' and the reference voltage VREF, the comparator COMP compares the ramp voltage VRAMP' with the reference voltage VREF and determines whether the ramp voltage VRAMP' and the reference voltage VREF are equal.

When the comparator COMP determines that the ramp voltage VRAMP' of the digital control rises to be equal to the reference voltage VREF, the comparator output signal S1 output by the output terminal of the comparator COMP will change from the original low level to the high level. When the comparator COMP determines that the ramp voltage VRAMP' of the digital control has not risen to be equal to the reference voltage VREF, the comparator output signal S1 output by the output terminal of the comparator COMP still maintains the original low level.

The two input terminals of the D-type flip-flop DFF respectively receive the comparator output signal S1 provided by the output terminal of the comparator COMP and the real-time count value provided by the ramp counter RCT. When the comparator output signal S1 changes from the original low level to the high level, It means that the digitally controlled ramp voltage VRAMP' rises to be equal to the reference voltage VREF, and the D-type flip-flop DFF will provide the feedback signal FB to the timing controller TCON according to the real-time count value provided by the ramp counter RCT.

At this time, the timing controller TCON can obtain the instantaneous count value of the ramp counter RCT when the digitally controlled ramp voltage VRAMP' rises to equal to the reference voltage.

Then, the timing controller TCON compares the instantaneous count value of the ramp counter RCT with the preset value, and selectively corrects the rising slope of the digitally controlled ramp voltage VRAMP' generated by the ramp voltage generator RVG according to the comparison result. In fact, the timing controller TCON can provide the slope control signal SLC to the ramp voltage generator RVG to selectively correct the rising slope of the digitally controlled ramp voltage VRAMP' generated by the ramp voltage generator RVG.

Please refer to Figure 4. Figure 4 shows that when the digitally controlled ramp voltage VRAMP' rises to the reference voltage VREF, the timing controller TCON of the present invention compares the instantaneous count value of the ramp counter RCT with the preset value N It is a timing chart for determining whether to correct the rising slope of the digitally controlled ramp voltage VRAMP' generated by the ramp voltage generator RCT.

When the digitally controlled ramp voltage VRAMP' starts to rise, the ramp counter RCT also starts counting from 1. When the digitally controlled ramp voltage VRAMP' rises to be equal to the reference voltage VREF, the timing controller TCON compares the instantaneous count value of the ramp counter RCT with the preset value N.

If the above comparison result is the real-time count value of the ramp counter RCT, etc. At the preset value N, the rising slope SL1 of the ramp voltage VRAMP' represented by the digital control is normal (or the oscillation frequency of the oscillator OSC is normal), then the timing controller TCON will maintain the digits generated by the ramp voltage generator RVG The rising slope of the controlled ramp voltage VRAMP' remains unchanged.

If the result of the above comparison is that the instantaneous count value of the ramp counter RCT is greater than the preset value N, it means that the rising slope SL2 of the digitally controlled ramp voltage VRAMP' is too low (or the oscillation frequency of the oscillator OSC is too fast), then the timing controller TCON increases the rising slope of the digitally controlled ramp voltage VRAMP' generated by the ramp voltage generator RVG, so that the rising slope of the digitally controlled ramp voltage VRAMP can return to normal.

If the result of the above comparison is that the instantaneous count value of the ramp counter RCT is less than the preset value N, it means that the rising slope SL3 of the digitally controlled ramp voltage VRAMP' is too high (or the oscillation frequency of the oscillator OSC is too slow), then the timing controller TCON will reduce the rising slope of the digitally controlled ramp voltage VRAMP' generated by the ramp voltage generator RVG, so that the rising slope of the digitally controlled ramp voltage VRAMP can return to normal.

In this way, even if the ramp voltage values sampled by different driving circuits on the display panel side may deviate from the normal value (as shown by the offset PVT in FIG. 4) due to process, voltage, and temperature variations, the present invention It can still dynamically correct the rising slope of the digitally controlled ramp voltage VRAMP' generated by the ramp voltage generator RVG according to the comparison result of the real-time count value of the ramp counter RCT and the preset value, so that different driving circuits are displayed on the display panel. The digitally controlled ramp voltage VRAMP’ The pressure values can all tend to be consistent.

Another specific embodiment according to the present invention is a voltage correction method. In this embodiment, the voltage correction method is applied to the display device. The display device includes a display panel, and the display panel can be an organic light-emitting diode panel, and can adopt OLED On Silicon microdisplay technology, but it is not limited to this. The display device also includes a timing controller, a ramp voltage generator, and a ramp counter. When the ramp voltage generator generates the ramp voltage, the ramp counter starts counting.

Please refer to Figure 5. FIG. 5 shows a flowchart of the voltage correction method in this embodiment.

As shown in Figure 5, the voltage correction method may include the following steps: Step S10: When the ramp voltage rises to be equal to the reference voltage, record the real-time count value of the ramp counter and send it back to the timing controller; Step S12: Timing control Step S14: If the comparison result of Step S12 is that the real-time count value is equal to the preset value, the timing controller maintains the rising slope of the ramp voltage unchanged; Step S16: If the comparison of step S12 The result is that the instant count value is greater than the preset value, the timing controller increases the rising slope of the ramp voltage; and step S18: if the comparison result of step S12 is that the instant count value is less than the preset value, the timing controller reduces the ramp voltage Rising slope.

Therefore, even if the ramp voltage values sampled by different driving circuits on the display panel may deviate from the normal value due to process, voltage, and temperature variations, the voltage correction method of the present invention can still be based on the instantaneous calculation of the ramp counter. Value and forecast The comparison result of the set value dynamically corrects the rising slope of the ramp voltage, so that the ramp voltage sampled by different driving circuits at the display panel end can be consistent.

In practical applications, the timing controller can be coupled to the ramp voltage generator and provide a slope control signal to the ramp voltage generator to selectively correct the rising slope of the ramp voltage generated by the ramp voltage generator.

In addition, the display device may further include a comparator. The two input terminals of the comparator are respectively coupled to the ramp voltage generator and the reference voltage. The comparator compares the ramp voltage with the reference voltage to determine whether the ramp voltage rises to be equal to the reference voltage.

In addition, the display device may further include a D-type flip-flop. The two input terminals of the D-type flip-flop are respectively coupled to the output terminal of the comparator and the ramp counter. The output terminal of the D-type flip-flop is coupled to the timing controller. When the ramp voltage rises to be equal to the reference voltage, the D-type flip-flop will return the instant count value provided by the ramp counter to the timing controller.

In addition, the display device may further include an oscillator. The oscillator is coupled to the ramp counter to provide an oscillation frequency to the ramp counter. The comparison result in step S12 is related to the oscillation frequency of the oscillator.

Compared with the prior art, the voltage correction circuit and voltage correction method applied to the display device according to the present invention can be judged based on the comparison result between the real-time count value of the ramp counter and the preset value when the ramp voltage rises to be equal to the reference voltage Whether the rising slope of the ramp voltage generated by the ramp voltage generator is too low or too high (or whether the oscillation frequency of the oscillator is too fast or too slow) and correct the rising slope of the ramp voltage accordingly, so it can be effective Improve due to process, voltage, temperature variation The same problem that the ramp voltage sampled by the driving circuit at the display panel also changes accordingly.

Through the detailed description of the preferred embodiments above, it is hoped that the characteristics and spirit of the present invention can be described more clearly, and the scope of the present invention is not limited by the preferred embodiments disclosed above. On the contrary, its purpose is to cover various changes and equivalent arrangements within the scope of the patent application for the present invention.

S10~S18: steps

Claims (16)

A voltage correction circuit applied to a display device. The voltage correction circuit includes: a ramp voltage generator for generating a ramp voltage; a ramp counter coupled to the ramp voltage generator, when the ramp voltage generator is When the voltage generator generates the ramp voltage, the ramp counter starts counting; and a timing controller, respectively coupled to the ramp voltage generator and the ramp counter, when the ramp voltage rises to be equal to a reference voltage When the timing controller compares a real-time count value of the ramp counter with a preset value, and selectively corrects the ramp wave voltage generator generated by the ramp wave voltage generator according to a comparison result of the real-time count value and the preset value The rising slope of the ramp voltage; wherein if the comparison result is that the real-time count value is equal to the preset value, the timing controller maintains the rising slope of the ramp voltage unchanged. The voltage correction circuit described in the first item of the scope of patent application, wherein the timing controller is coupled to the ramp voltage generator and provides a slope control signal to the ramp voltage generator to selectively correct the ramp voltage The rising slope of the ramp voltage generated by the generator. A voltage correction circuit applied to a display device. The voltage correction circuit includes: a ramp voltage generator for generating a ramp voltage; a ramp counter coupled to the ramp voltage generator, when the ramp voltage generator is When the voltage generator generates the ramp voltage, the ramp counter starts counting; and a timing controller, respectively coupled to the ramp voltage generator and the ramp counter, when the ramp voltage rises to be equal to a reference voltage When, the timing controller compares a real-time count value of the ramp counter with a preset value and selectively adjusts it according to a comparison result of the real-time count value and the preset value. The rising slope of the ramp voltage generated by the ramp voltage generator is positive; wherein if the comparison result is that the instantaneous count value is greater than the preset value, the timing controller increases the rising slope of the ramp voltage. The voltage correction circuit described in item 3 of the scope of patent application, wherein the timing controller is coupled to the ramp voltage generator and provides a slope control signal to the ramp voltage generator to selectively correct the ramp voltage The rising slope of the ramp voltage generated by the generator. A voltage correction circuit applied to a display device. The voltage correction circuit includes: a ramp voltage generator for generating a ramp voltage; a ramp counter coupled to the ramp voltage generator, when the ramp voltage generator is When the voltage generator generates the ramp voltage, the ramp counter starts counting; and a timing controller, respectively coupled to the ramp voltage generator and the ramp counter, when the ramp voltage rises to be equal to a reference voltage When the timing controller compares a real-time count value of the ramp counter with a preset value, and selectively corrects the ramp wave voltage generator generated by the ramp wave voltage generator according to a comparison result of the real-time count value and the preset value The rising slope of the ramp voltage; wherein if the comparison result is that the real-time count value is less than the preset value, the timing controller reduces the rising slope of the ramp voltage. The voltage correction circuit described in item 5 of the scope of patent application, wherein the timing controller is coupled to the ramp voltage generator and provides a slope control signal to the ramp voltage generator to selectively correct the ramp voltage The rising slope of the ramp voltage generated by the generator. A voltage correction circuit applied to a display device. The voltage correction circuit includes: A ramp wave voltage generator for generating a ramp wave voltage; a ramp wave counter, coupled to the ramp wave voltage generator, when the ramp wave voltage generator generates the ramp wave voltage, the ramp wave counter starts counting; A timing controller is respectively coupled to the ramp voltage generator and the ramp counter. When the ramp voltage rises to be equal to a reference voltage, the timing controller compares a real-time count value of the ramp counter with a Preset value and selectively correct the rising slope of the ramp voltage generated by the ramp voltage generator according to a comparison result of the real-time count value and the preset value; a comparator, two input terminals of the comparator Respectively coupled to the ramp voltage generator and the reference voltage, the comparator compares the ramp voltage with the reference voltage to determine whether the ramp voltage rises to be equal to the reference voltage; and a D-type flip-flop, The two input terminals of the D-type flip-flop are respectively coupled to the output terminal of the comparator and the ramp counter. The output terminal of the D-type flip-flop is coupled to the timing controller. When the ramp voltage rises to and When the reference voltages are equal, the D-type flip-flop returns the real-time count value provided by the ramp counter to the timing controller. A voltage correction circuit applied to a display device. The voltage correction circuit includes: a ramp voltage generator for generating a ramp voltage; a ramp counter coupled to the ramp voltage generator, when the ramp voltage generator is When the voltage generator generates the ramp voltage, the ramp counter starts counting; and a timing controller, respectively coupled to the ramp voltage generator and the ramp counter, when the ramp voltage rises to be equal to a reference voltage When, the timing controller compares a real-time count value of the ramp counter with a preset value and selectively adjusts it according to a comparison result of the real-time count value and the preset value. Positive the rising slope of the ramp voltage generated by the ramp voltage generator; and an oscillator, coupled to the ramp counter, for providing an oscillation frequency to the ramp counter, and the comparison result is the same as the oscillation frequency related. A voltage correction method is applied to a display device. The display device includes a timing controller, a ramp voltage generator and a ramp counter. When the ramp voltage generator generates a ramp voltage, the ramp counter To start counting, the voltage correction method includes the following steps: (a) when the ramp voltage rises to be equal to a reference voltage, record a real-time count value of the ramp counter and send it back to the timing controller; (b) The timing controller compares the real-time count value with a preset value; (c) the timing controller selectively corrects the rising slope of the ramp voltage generated by the ramp voltage generator according to the comparison result of step (b) . For example, in the voltage correction method described in item 9 of the scope of patent application, if the comparison result of step (b) is that the real-time count value is equal to the preset value, then in step (c), the timing controller maintains the ramp wave The rising slope of the voltage does not change. For example, the voltage correction method described in item 9 of the scope of patent application, wherein if the comparison result of step (b) is that the real-time count value is greater than the preset value, then in step (c), the timing controller adds the ramp wave The rising slope of the voltage. For example, in the voltage correction method described in item 9 of the scope of patent application, if the comparison result of step (b) is that the real-time count value is less than the preset value, then in step (c), the timing controller reduces the ramp wave The rising slope of the voltage. According to the voltage correction method described in claim 9, wherein the timing controller is coupled to the ramp voltage generator and provides a slope control signal to the ramp voltage generator to selectively correct the ramp voltage The oblique generated by the generator The rising slope of wave voltage. For the voltage correction method described in claim 9, wherein the display device further includes a comparator, two input terminals of the comparator are respectively coupled to the ramp voltage generator and the reference voltage, and the comparator compares the The ramp voltage and the reference voltage are used to determine whether the ramp voltage rises to be equal to the reference voltage. According to the voltage calibration method described in claim 14, wherein the display device further includes a D-type flip-flop, and two input terminals of the D-type flip-flop are respectively coupled to the output terminal of the comparator and the ramp wave Counter, the output terminal of the D-type flip-flop is coupled to the timing controller, and when the ramp voltage rises to be equal to the reference voltage, the D-type flip-flop provides the instant counter provided by the ramp counter The value is passed back to the timing controller. According to the voltage calibration method described in claim 9, wherein the display device further includes an oscillator coupled to the ramp counter for providing an oscillation frequency to the ramp counter, and the comparison result of step (b) It is related to an oscillation frequency of the oscillator.

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